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Tennis: Australian Open - Djokovic makes progresss after gutsy performance from veteran Hewitt

Lleyton Hewitt rolled back the years tonight to deliver a typically gutsy display but it was not enough to derail Novak Djokovic's title defence at the Australian Open.

Hewitt looked down and out at two sets and 3-0 down but he stormed back to take the contest to a fourth set in which the world number one showed battling qualities of his own to edge through 6-1 6-3 4-6 6-3 in nearly three hours.

For so long, it was one-way traffic with Hewitt looking flat and tired after his exertions against Andy Roddick and Milos Raonic in the previous rounds.

And Djokovic took full advantage, three breaks handing him the first set and three more moving him two sets up.

And when he won the first three games of the third, it seemed just a matter of time before victory was secured.

But, from nowhere, Hewitt found some form and, all of a sudden, Djokovic looked rattled. The 30-year-old from Adelaide, twice a grand slam champion, dragged it back to 3-3, broke again for a 5-4 lead and then served it out.

And when Djokovic faced another break point in the third game of the fourth set, the comeback looked set to continue. But the Serbian held his nerve to win the game and with that he regained the momentum.

He claimed the Hewitt serve to go 4-2 up and it proved a lead he would not relinquish.

"I have to give credit to my opponent who never gives up," said Djokovic.

"He's a great competitor and he kept on making me play an extra shot. I made a couple of unforced errors and he got back into the match. I have a lot of respect for him.

"For two sets and 3-0 I was playing really well and then I stopped moving but credit to him, he wasn't making any unforced errors."

Next for Djokovic is a meeting with fifth seed David Ferrer in the last eight.

The Spaniard was an impressive winner today, beating the dangerous Richard Gasquet 6-4 6-4 6-1.

The other quarter-final in the top half will be between Andy Murray and Kei Nishikori after both men progressed today - albeit via different methods.

Fourth seed Murray spent just 49 minutes on court before Mikhail Kukushkin succumbed to a hip flexor injury while Nishikori had to fight for three-and-a-half hours to get the better of Jo-Wilfried Tsonga 2-6 6-2 6-1 3-6 6-3.

In the process, Nishikori became the first Japanese man to reach the last eight at this event in 80 years.

Having reached the quarter-finals of a grand slam for the first time in his career, he said: "I am feeling unbelievable, to beat Tsonga makes me really happy.

"This is the first quarter-final for me, my best result previously was getting to the round of 16 at the US Open in 2008. I played well at the end of last year and now this. I feel like I'm stepping up."

Nishikori is rapidly becoming a superstar in his homeland and results like this will only increase his popularity.

"Hopefully it's big in Japan, I'm really excited," he added.

"Hopefully people, especially kids, will start playing tennis. But first of all I have to play well and I have to give them good news.

"But if that helps Japan then I'm really happy."

Sixth seed Tsonga, a runner-up here in 2008, admitted Nishikori's superior mobility had given him the edge.

"It was tough, I had a good opponent today," said the Frenchman.

"I didn't play good tennis and I didn't control everything. It was not a nice moment for me.

"He's tough to play because he runs a lot and everything comes back."

The drama of the Nishikori-Tsonga match was in stark contrast to the non-contest of Murray-Kukushkin.

The Kazakh beat Gael Monfils in five gruelling sets in the previous round and those exertions seemed to hinder him from the start as Murray cruised into a 6-1 6-1 1-0 lead before Kukushkin pulled out.

"I played him a few weeks ago (in Brisbane) and it was a tough match," said Murray. "I expected another one today but it's so hot.

"I get to conserve a bit of energy but he was obviously struggling.

"When I saw him struggling I was just trying to get a few serves in and get him running."